frontend dashboard: "hard errors" can show as two entries due to multiple frontend instances

Created by: slimsag

To fix:

-(sum by (status)(increase(src_graphql_search_response{status=~"error"}[5m]))) or on() vector(0)
+sum(sum by (status)(increase(src_graphql_search_response{status=~"error"}[5m]))) or on() vector(0)